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41.
Any continuous bivariate distribution can be expressed in terms of its margins and a unique copula. In the case of extreme‐value distributions, the copula is characterized by a dependence function while each margin depends on three parameters. The authors propose a Bayesian approach for the simultaneous estimation of the dependence function and the parameters defining the margins. They describe a nonparametric model for the dependence function and a reversible jump Markov chain Monte Carlo algorithm for the computation of the Bayesian estimator. They show through simulations that their estimator has a smaller mean integrated squared error than classical nonparametric estimators, especially in small samples. They illustrate their approach on a hydrological data set. 相似文献
42.
The authors extend the block external bootstrap to partially linear regression models with strongly mixing, nonstationary error terms. In addition to providing an approximate distribution for the semiparametric least square estimator of the parametric component, they propose a consistent estimator of the co‐variance matrix of this estimator. 相似文献
43.
Valerie Goby 《Asian Ethnicity》2004,5(2):235-244
In Singapore, government policy is for equal but separate development of the four major ethnic groups—Chinese, Malay, Indian and other. In this study, I attempt to gain some preliminary views of how strongly women identify with their own ethnic group and how freely they are prepared to interact with people from other ethnic groups in non‐work‐related situations. I confine my study to females for two reasons. One is that traditional ethnic dress is common among females in Singapore but much rarer among men, and this makes a strong non‐verbal statement of identity. The second reason is to avoid differences between males and females, which I did not wish to pursue within the limits of this exploratory study. The findings of my pilot investigation indicate that intra‐ethnic spontaneous interaction is more likely to occur among women who display a strong national identity. Moreover, younger women, who were exposed during their school years to the government's recent drive to nurture ethnic and cultural differences, are less open to inter‐ethnic interaction than are women in their 30s and older, who grew up when the government drive was towards creating one common national identity for the people of Singapore. 相似文献
44.
从生态、生产和遗传育种等方面分析了四川小麦多小穗育种的理论依据,并就多小穗品种绵农2号的选育方法进行了讨论。这些方法有:(1)多组合小群体确定目标组合;(2)在目标组合中确定重点目标组合;(3)在重点目标组合中确定重点株系;(4)进行阶梯式杂交。 相似文献
45.
Given the fragmented structure of child‐care assistance in the United States, it has been difficult to obtain accurate estimates of which families are assisted, through which mechanisms, and at what level. Making use of survey data from New York City, we analyze the distribution of several forms of public child‐care assistance. Results suggest that about 40% of all families with young children receive some form of child‐care assistance. Considering all forms of assistance, the distribution of child‐care help is targeted in both expected and some unexpected ways. Implications of these results are discussed in the context of U.S. child‐care policies governing access and benefit levels. 相似文献
46.
Formulae are provided that define the ‘bend points’, the beginning and end of the essentially linear dose–response region, for the four‐parameter logistic model. The formulae are expressed in both response and dose units. The derivation of the formulae is shown in order to illustrate the general nature of the methodology. Examples are given that describe how the formulae may be used while planning and conducting bioassays. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
47.
通过研究绿色壁垒对我国农产品出口的影响,探讨可持续植保对消除绿色壁垒的可行性,认为发展可持续植保是消除绿色壁垒的重要策略,并阐述了完善可持续植保体系的具体措施,针对绿色壁垒的具体形式提出了相应的对策。 相似文献
48.
Sally Walters 《Gender, Work and Organization》2005,12(3):193-216
This article uses data from 50 qualitative interviews with female part‐time workers in low‐level jobs in Britain to illustrate their attitudes, orientations and aspirations towards paid work. The research reports two main findings. Firstly, even female part‐time workers at the bottom end of the occupational structure are not a homogeneous group of workers. Secondly, they are not all highly satisfied with their jobs. The article argues that many women (especially those in working‐class households) still do not have a genuine choice between ‘family work’ and ‘market work’. It concludes by presenting a theoretical model of orientations to work. 相似文献
49.
David Oakes 《Revue canadienne de statistique》2005,33(3):465-468
The author characterizes the copula associated with the bivariate survival model of Clayton (1978) as the only absolutely continuous copula that is preserved under bivariate truncation. 相似文献
50.
Christine Jones 《Child & Family Social Work》2016,21(1):85-93
One significant change in adoption practice that has occurred over the last four decades is the shift away from an expectation of confidentiality towards an expectation of openness in adoption. Openness is typically conceived in terms of the level of contact between adoptive and birth families following adoption or the extent to which adoption is openly discussed within the adoptive family. While these shifts in practice have generated controversy, they are largely supported by research evidence and have become a feature of contemporary adoptive family life. As a result, the narrative that has emerged in relation to openness in adoption is one of historical progress. In this paper, I argue that the lived reality of adoption is less straightforward than this narrative suggests. An analysis of the social and cultural context in which adoption operates suggests instead that the persistent feature of adoption throughout this historical period of increasing openness can be more accurately described as a state of enduring ambiguity regarding the nature of post‐adoption relationships. The paper highlights the potentially damaging consequences of overlooking this aspect of adoptive family life and comments on the role of policy in shaping openness in adoption. 相似文献